2024/02/09 by Toke Vibel, Mikkel Berg Christensen, Morten Bondo Christensen +8 · 1 voice
Chemistry · Physics and Astronomy · #Absorption (acoustics) #Atomic and Subatomic Physics Research #Calibration #Cold Atom Physics and Bose-Einstein Condensates #Environmental science #Geography #Optics #Physics #Remote sensing #Spectroscopy and Laser Applications #cond-mat.quant-gas #physics.atom-ph
paper · pdf · doi:10.1088/1361-6455/ad53ae
arxiv published 2024/02/09 · arxiv updated 2024/02/09 · openalex publication_date 2024/06/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The accurate determination of atom numbers is an ubiquitous problem in the field of ultracold atoms. For modest atom numbers, absolute calibration techniques are available, however, for large numbers and high densities, the available techniques neglect many-body scattering processes. Here, a spatial calibration technique for time-of-flight absorption images of ultracold atomic clouds is presented. The calibration is obtained from radially averaged absorption images and we provide a practical guide to the calibration process. It is shown that the calibration coefficient scales linearly with optical density and depends on the absorbed photon number for the experimental conditions explored here. This allows for the direct inclusion of a spatially dependent calibration in the image analysis. For typical ultracold atom clouds the spatial calibration technique leads to corrections in the detected atom number up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mo>≈</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> and temperature up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mo>≈</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>14</mml:mn> </mml:mrow> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> in comparison to previous calibration techniques. The technique presented here addresses a major difficulty in absorption imaging of ultracold atomic clouds and prompts further theoretical work to understand the scattering processes in ultracold dense clouds of atoms for accurate atom number calibration.